Alcohol consumption during pregnancy is a significant public health problem and can result in a continuum of adverse outcomes to the fetus known as fetal alcohol spectrum disorders (FASD). These disorders range from growth retardation to neurobehavioral alterations including mental health problems, poor social adjustment and poor stress tolerance. Fetal alcohol defects range from diminution in the size of the brain region to microstructural pathology at the level of loss of neurons and glial cells, ectopic locations of neurons and glia, or defects in fiber tracts. The neurotoxic actions of ethanol during development reduce the number of hippocampal neurons, cortical neurons, cerebral granule and Purkinje neurons and hypothalamic neurons. Our work and that of others have shown that alcohol metabolism releases bi-products, such as acetaldehyde and reactive oxygen species (ROS), which can cause DNA damage and in conditions of DNA repair deficiencies can lead to genomic instability and cell death. Recent investigation of possible epigenetic mechanisms involving DNA methylation and histone modifications as mediators of alcohol's adverse effects on the brain of the fetus provides a promising approach for understanding the complex observable characteristics associated with FAS. Unfortunately, to this point, all of the methods that have been used to study epigenetic modifications of genes causing many fetal alcohol syndrome phenotypes rely on static measurements. We believe that quantifying histone turnover might be an important parameter that can contribute to better understanding of epigenetic regulation of gene expression in developing brain. Our central hypothesis is that histone turnover might be an important parameter that can contribute to the ethanol-mediated epigenetic alterations leading to defects in gene expression and cell survival. We propose to use a novel stable isotope tracer method that we recently developed, which enables measurements of protein synthesis and turnover in vivo, to answer this question. The studies outlined in this proposal will couple standard proteomic analyses with our kinetic method using heavy water labeling and LC-MS/MS to simultaneously measure the half-life and abundance of core histones, histone variants and their post-translationally modified isoforms and determine the functional significance of histone turnover on gene expression and protein network, with specific emphasis on DNA damage response pathways. The proposed studies are highly innovative as they would be the first to characterize histone kinetics in the developing brain, they may also identify new areas for therapeutic intervention as well as markers for fetal alcohol spectrum disorders.